Infraspecific variability in the volatile leaf oils of Chamelaucium uncinatum (Myrtaceae)

Variation in leaf essential oils and morphometric characters among 38 locations of Chamelaucium uncinatum were used to describe infraspecific diversity and geographic patterns of variation. Four chemical types were designated: citronellal, α-pinene or limonene dominant, or one in which all three monoterpenes were co-dominant. The citronellal and limonene types were geographically restricted but the α-pinene and co-dominant types were widespread. The citronellal type also demonstrated higher diversity (by Shannon-Weiner index) in the oil profile than the other types. Biochemical differentiation was not strongly paralleled by morphological differences between chemotypes; only the citronellal-type differed morphologically from the other three types with respect to floral bud and leaf characters. Based on biochemical and morphological differences, and geographic localization, it was concluded that the citronellal type may represent a recently evolved ecotype of C. uncinatum.